Python 3.13 in CI

.github/workflows/ci-additional.yaml

@@ -41,7 +41,7 @@ jobs:
 
     env:
       CONDA_ENV_FILE: ci/environment.yml
-      PYTHON_VERSION: "3.12"
+      PYTHON_VERSION: "3.13"
 
     steps:
       - uses: actions/checkout@v4
@@ -95,7 +95,7 @@ jobs:
         shell: bash -l {0}
     env:
       CONDA_ENV_FILE: ci/environment.yml
-      PYTHON_VERSION: "3.12"
+      PYTHON_VERSION: "3.13"
 
     steps:
       - uses: actions/checkout@v4

.github/workflows/ci.yaml

@@ -26,14 +26,14 @@ jobs:
       matrix:
         os: ["ubuntu-latest"]
         env: ["environment"]
-        python-version: ["3.10", "3.12"]
+        python-version: ["3.10", "3.13"]
         include:
           - os: "windows-latest"
             env: "environment"
-            python-version: "3.12"
+            python-version: "3.13"
           - os: "ubuntu-latest"
             env: "no-dask" # "no-xarray", "no-numba"
-            python-version: "3.12"
+            python-version: "3.13"
           - os: "ubuntu-latest"
             env: "minimal-requirements"
             python-version: "3.10"

.github/workflows/testpypi-release.yaml

@@ -23,8 +23,6 @@ jobs:
 
       - uses: actions/setup-python@v5
         name: Install Python
-        with:
-          python-version: "3.12"
 
       - name: Install dependencies
         run: |
@@ -64,8 +62,6 @@ jobs:
     steps:
       - uses: actions/setup-python@v5
         name: Install Python
-        with:
-          python-version: "3.12"
       - uses: actions/download-artifact@v4
         with:
           name: releases

.github/workflows/upstream-dev-ci.yaml

@@ -34,7 +34,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.12"]
+        python-version: ["3.13"]
     steps:
       - uses: actions/checkout@v4
         with:

flox/aggregations.py

@@ -590,6 +590,7 @@ class Scan:
     identity: Any
     # dtype of result
     dtype: Any = None
+    preserves_dtype: bool = False
     # "Mode" of applying binary op.
     # for np.add we apply the op directly to the `state` array and the `current` array.
     # for ffill, bfill we concat `state` to `current` and then run the scan again.
@@ -719,16 +720,18 @@ def scan_binary_op(left_state: ScanState, right_state: ScanState, *, agg: Scan)
     reduction="nanlast",
     scan="ffill",
     # Important: this must be NaN otherwise, ffill does not work.
-    identity=np.nan,
+    identity=dtypes.NA,
     mode="concat_then_scan",
+    preserves_dtype=True,
 )
 bfill = Scan(
     "bfill",
     binary_op=None,
     reduction="nanlast",
     scan="ffill",
     # Important: this must be NaN otherwise, bfill does not work.
-    identity=np.nan,
+    identity=dtypes.NA,
+    preserves_dtype=True,
     mode="concat_then_scan",
     preprocess=reverse,
     finalize=reverse,

flox/core.py

@@ -2823,9 +2823,6 @@ def groupby_scan(
         # nothing to do, no NaNs!
         return array
 
-    is_bool_array = np.issubdtype(array.dtype, bool)
-    array = array.astype(np.int_) if is_bool_array else array
-
     if expected_groups is not None:
         raise NotImplementedError("Setting `expected_groups` and binning is not supported yet.")
     expected_groups = _validate_expected_groups(nby, expected_groups)
@@ -2855,6 +2852,11 @@ def groupby_scan(
     if array.dtype.kind in "Mm":
         cast_to = array.dtype
         array = array.view(np.int64)
+    elif array.dtype.kind == "b":
+        array = array.view(np.int8)
+        cast_to = None
+        if agg.preserves_dtype:
+            cast_to = bool
     else:
         cast_to = None
 
@@ -2869,6 +2871,7 @@ def groupby_scan(
             agg.dtype = np.result_type(array.dtype, np.uint)
     else:
         agg.dtype = array.dtype if dtype is None else dtype
+    agg.identity = xrdtypes._get_fill_value(agg.dtype, agg.identity)
 
     (single_axis,) = axis_  # type: ignore[misc]
     # avoid some roundoff error when we can.
@@ -2887,7 +2890,7 @@ def groupby_scan(
 
     if not has_dask:
         final_state = chunk_scan(inp, axis=single_axis, agg=agg, dtype=agg.dtype)
-        result = _finalize_scan(final_state)
+        result = _finalize_scan(final_state, dtype=agg.dtype)
     else:
         result = dask_groupby_scan(inp.array, inp.group_idx, axes=axis_, agg=agg)
 
@@ -2940,9 +2943,9 @@ def _zip(group_idx: np.ndarray, array: np.ndarray) -> AlignedArrays:
     return AlignedArrays(group_idx=group_idx, array=array)
 
 
-def _finalize_scan(block: ScanState) -> np.ndarray:
+def _finalize_scan(block: ScanState, dtype) -> np.ndarray:
     assert block.result is not None
-    return block.result.array
+    return block.result.array.astype(dtype, copy=False)
 
 
 def dask_groupby_scan(array, by, axes: T_Axes, agg: Scan) -> DaskArray:
@@ -2985,7 +2988,7 @@ def dask_groupby_scan(array, by, axes: T_Axes, agg: Scan) -> DaskArray:
     )
 
     # 3. Unzip and extract the final result array, discard groups
-    result = map_blocks(_finalize_scan, accumulated, dtype=agg.dtype)
+    result = map_blocks(partial(_finalize_scan, dtype=agg.dtype), accumulated, dtype=agg.dtype)
 
     assert result.chunks == array.chunks
 

pyproject.toml

@@ -14,6 +14,7 @@ classifiers = [
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
+    "Programming Language :: Python :: 3.13",
 ]
 dependencies = [
     "pandas>=1.5",